The present invention relates to a method for changing an operating mode in an assembly with a combustion engine and an electric machine which are coupled with each other via a planetary gear train, an assembly with a combustion engine with a crankshaft and an electric machine with a rotor, which are coupled with one another via a planetary gear train, and a motor vehicle with such assembly.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
It is the objective of this assembly to operate the electric machine both as a starter motor for the combustion engine and as a generator driven by the combustion engine. Different gear ratios can be set by suitable placement of clutches and/or overrunning clutches in the planetary gear train or between other elements of the assembly. For example, the electric machine rotates relatively faster preferably during startup of the combustion engine than when the electric machine operates as a generator.
It will be assumed here that a specific clutch, upon closing, adjusts the gear ratio between the electric machine and the combustion engine to a fixed value, whereas when the clutch is open, either no fixed value is set or another value is set—this can be defined by other clutches and overrunning clutches.
To date, friction clutches have been used in such assemblies. However, these have large dimensions, because they must transmit large torques in particular during startup of the combustion engine.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide an approach for reducing the overall dimensions of the assembly.